1,4-Dioxane In Drinking Water: What You Need To Know

What Is 1,4 Dioxane?

1,4 dioxane is a synthetic industrial chemical, typically used as a stabilizer for chlorinated solvents. It was historically used in the production of 1,1,1-trichloroethane (TCA), which was phased out in 1985 after scientists determined it to be an ozone-depleting substance. Today, 1,4 dioxane is not typically added directly to consumer products but can be an unintentional byproduct in certain plastics.

Is 1,4-Dioxane Regulated?

For drinking water, no. 1,4, dioxane is not federally regulated under the Safe Drinking Water Act even though EPA has classified it as “likely to be carcinogenic to humans by all exposure routes.” There are health advisories in place but a Maximum Contaminant Level (MCL) does not exist. 1,4-dioxane is regulated by the Occupational Safety and Health Administration (OSHA) for indoor workplace air quality.

How Does 1,4 Dioxane Enter Drinking Water?

1,4-dioxane is typically found in areas close to production facilities that either make it or use it as a solvent. According to the Agency for Toxic Substances and Disease Registry, 1,4-dioxane can easily travel into groundwater because it does not stick to soil particles.

Health Effects of 1,4-Dioxane In Drinking Water:

1,4-dioxane is associated with an increased risk of nasal, liver, and gallbladder cancers. Like other contaminants, the dose and duration of exposure affect the likelihood of adverse health effects.

Regulatory History of 1,4-Dioxane:

1,4-dioxane is on the fourth drinking water Contaminant Candidate List and is also part of the Third Unregulated Contaminant Monitoring Rule. A Maximum Contaminant Level (MCL) has not been set for 1,4 dioxane. This means that unless a state standard exists, utility providers are not required to remove it from drinking water. As of November 2017, 18 states set drinking water and groundwater guidelines for 1,4-dioxane.